Speed control for sound record medium



WOOLF I 2,221,661 SPEED CONTROL FOR SOUND RECORD MEDIUM Nov. 12, 1940.

Fild March 22, 1940 INVENTOR V/Az/A/v A. W004- ATTORNEY Patented Nov. 12, 1940 UNITED I STATES- 2,221,661 H srann comor. FOR. SOUND RECORD MEDIUM WllliamL,Wooli', Bayside, Long Island, N. Y., as signer to Recordgraph CorporatiomNew York, N.'Y, a corporation of Delaware Application March 22, 1940. Serial No. 325.290

10 Claims. (01. 271-23) The present invention relates to sound recording and reproducing mechanism and more particularly to means whereby a uniform speed is given to the recordmedium. d

An object of the invention is to provide a speed control which will P rmit the use of a relatively small high speed motor. and to transmit the power of this motor to the film propelling means in a substantially noiseless manner. 'A further object is to provide a high speed motor for furnishing power to the film propelling means and controlling the speed of the motor through the medium of a high speed'low mass fly wheel.

Further objects include the provision of means to render operative or inoperative the connections between the motor and the high speed fly wheel.

It is highly important for good recording and reproducing that the record medium be propelled at a uniform speed. Where themes of the record medium is substantial, as'for instance, in

the case of a phonograph disc supported on a turntable, the turntabie'and record themselves act somewhat as a fly wheel. When, however,

the record medium consists of a film of extreniely small mass, the problem of speed control is more complicated. In selecting a type of motor for use in propellingsuch a film, a compromise must be made between motors of high speed and motors oflow speed. Low speed motors have high mass but low power, and have the advantage of being relatively freer from vibration than high speed small motors. The motor contemplated for use in the present invention is relatively small andof relatively high speed; for .instance'3,600 revolutions per minute maybe taken as an ex-. ample. The record film is advanced at a relatively low rate of speed, as for example 40 or 50 feet'per minute, A fly wheel of suitable diameter and mass is provided, and to bring about the desired speed reductions between the motor and film, which is driventhrough the fly wheel, the motor pulley must be small. To avoid vibration noise, the motor pulley should be of resilient material, such as rubber in order that its drive is relatively silent. An objection to a rubber pulley on the motor shaft directly engaging the fly wheel is due to the fact that such a'pulley becomes smaller in diameter due to wear thereby causing a reduction of fly wheel speed. Similar objections apply to covering the flywheel with a rubber rim. Such a construction, moreover, is expensive and does not wear well.

A feature of the present invention relates to the employment of a rubber idler roller between the metal motorpulley and the metaljfly wheel. The reduction in size for such a rubber pulley by wear, does not changespeed on the flywheel, 5, and of course, the motor pulley and fly wheel being of metal, do not change their shape or size to any appreciable extentdue to wear by the rubber roller.

If such an idler pulley during prolonged perio I ods'of non-use were in constant contact with the motor pulley and the fly wheel," the pressure which necessarily must be exerted in order to create sufficient' friction for the transmission of power, wouldtend'to cause distortion of'the rubber roller, such roller becomingsomewhat elliptical or it may develop a'flat side, either of which conditions, causes a jerkyoperation.

A further feature of the invention, therefore, relates to the provision of means whereby distortion of the rubber idler is avoided.

- "It has been stated that uniform speed control is preferably accomplished in the present invention bysupplying a high speed flywheel or relatively smallv mass. This high speed fly-wheel, 25 however, is-not connecteddir'e'ctly to the motor through the rubber idler above referred to, but

is connected to a fly wheel of relatively large mass and the connecting meansjalso consists of a rubber roller by which power is transmitted from the fly wheel of relatively large mass to the high speed flywheel. v

The details of construction whereby the vari-' ous objects of the invention are accomplished, will best be understood from'the following description and claims when taken in connection with the accompanying drawing in which:

The figure is a diagrammatic perspective view of those parts of the'mechanism necessary to an understandingof its operation and function.

Referring to the drawing, the record medlum l in the form of a film; may be'propelled through the'machine in any desired manner. Inthe present embodiment, a sprocket 2 mounted on a shaft 4 is provided with teeth 5 which engage perforations 6 formed in the film. A sound'head I, which may be either a recording head or. a

reproducing head, is mounted adjacent the film.

Secured to theshaft 4 is a relatively large fly wheel 8.

Power for rotating fly wheel; and thereby propelling the film through the medium of the shaft 4 and sprocket 5 is provided by a motor l0 whose shaft carries a metal pulley l l. ,Thispulley is adapted to engage a rubber roller l2 mounted on a stub shaft l3 carried by an arm 13 pivoted at l3. A spring l1 normally tends to move the arm l3 and its rubber roller l2 to a position to disengage the roller l2 from the fly wheel 3. A stop I3 is provided to limit such movement of the arm l3 under action of its spring. The motor is supported in a base l3 and is capable of a slight rocking motion on its pivots 23, only one of which is shown in the drawing. A spring 2| connected to the motor and to some stationary part of the machine tends to rock the motor in an anti-clockwise direction to cause the motor pulley II to make contact with the rubber roller l2 and to press said roller against the periphery of the fly wheel 3 with sufllcient pressure to transmit the power of the motor to said fly wheel. The ratio of transmission is such that the fly wheel 3 rotates relatively slowly as compared with the motor. I

In the drawing the rubber roller I2 is disengaged from both the fly wheel 3 and the motor pulley H, the roller l2 being held disengaged through the action of the spring II.

The motor is maintained in the position shown in the drawing by means of a cam 22 secured to shaft 23, the cam engaging a part 23 projecting from the motor casing. With the cam 22 in the. position shown, the power of the spring 2| is overcome vand the pulley I is disengaged from the rubber roller l2. It is apparent that if the cam 22 were moved in a clockwise direction, through a sufficient angle, the spring 2| would then act. to rock the motor about its pivotal points and cause the motor pulley II to press the rubber roller l2 against the fly wheel 3.

While the fly wheel 3 has been referred to as having relatively large mass, this designation is intended for purposes of description and not as o a limitation. In fact the flywheel 8 is in the present invention of much smaller mass than usually required because of the provision of a second high speed fly wheel by which the speed of propulsion of the film is primarily controlled. This high speed fly wheel is indicated at 24 and its shaft 25 is pivoted to arms 23 and 21, the

latter arm being formed as apart of the arm 23 as shown. Secured to the shaft 23 beyond the arm 21 is a second rubber roller 23 which may be engaged with and disengaged from contact with the fly wheel 8. A spring 29 connected to the arm 23 and to a stationary part of the.

machine urges the arm 23 in a clockwise direction to cause the roller 28 to engage the fly wheel 3. Under the conditions shown in the drawing, the action of the spring 23, however, is resisted by a cam 33, also secured to the shaft 23. The cam, as positioned in the drawing, acts to hold roller 23 out of engagement with the fly wheel 3.

The shaft 23 in addition to controlling the" position of the cams 22 and also controls the closing end the shaft 23 carries a downwardly extending arm 32, the lower end of which engages the yoke-like member 33 which in a manner well known in the art, operates a switch, located in a switch box 34. The shaft 23 is rotated in one direction or the other by a knob 33 secured to its left hand end. The current for the motor is supplied from some source of electrical energy indicated at A and B. With the parts positioned as shown in the drawing, movement of the shaft 23 in a clockwise direction first causes the arm 32 to rock the yoke 33 and thereby close the motor circuit. The motor immeand opening of the motor circuit. To this I 22, however, is soshaped that this first movement of the shaft 23 does not permit the motor to be rocked. Further movement however, of the shaft 23 and cam 22 permits the spring 2| to become effective to rock the motor about its pivots to thereby cause the rubber roller i2 to be pressed against the'fly wheel 3 through the medium 01 the motor pulley diately starts. The cam ll. So far, however, the cam 33 continues to hold the arm 23 in position so that the roller 23 is, disengaged from the fly wheel 3. As the motor speeds up and the wheel 3 acquires momentum, the cam 33 releases the arm 23 which moves under action of the spring 23 to engage the roller 23 with the fly wheel 3.

The shaft 23 also carries a potentiometer 33 having a pointer 33. The potentiometer is ineffective while the knob 33 is moving from "of!" position to on position. During such movement, however, the several operations, above described, take place. Thereafter the potentiometer becomes effective and may be in the input volume control on an amplifier 33 used in either recording or reproducing. In reproducing the potentiometer is connected through the amplifier to a loud speaker 32. v

By this sequence of operation, the motor is first started without load. Itspulley ll then.

presses against the rubber roller i2 and the fly wheel 3 begins to rotate. When the fly wheel has attained sufficient momentum, the high speed fly wheel 24 is engaged with the fly wheel 3. Thus a load of considerable magnitude may be imposed upon a small motor whereas if the entire load were imposed with the motor standing still, it would in all probability not start and the windings might be damaged.

The roller 23 is small in diameter compared with the fly wheel 3, in consequence of' which the fly wheel 23 rotates at high velocity and tends tokeep the feed of the film uniform.

When the shaft 23 is returned to normal posi-. tion by rotation of the knob 33, anti-clockwise, the first result is to disconnect roller 23 vfrom fly wheel 3. Next roller l2 is disconnected and lastly the motor is deenergized.

What I claim is:

1. In a recording or reproducing mechanism, means for propelling a record medium in the form of a film, a fly wheel for controlling the motion of said propelling means, a second fly wheel normally disconnected from said first mentioned fly wheel,and means for connecting said second fly wheel to the first fly wheel when the latter has acquired momentum. I

2. In a recording or reproducing mechanism, means for propelling a record medium in the form of a fllm, a fly wheel for controlling the motion of said propelling means, a motor for driving said fly wheel, and a connection from said motor to said flv wheel normally disconnected from both the fly wheel and motor.

3. In a recording or reproducing mechanism, means for propelling a record medium in the form of a fllm, a fly wheel for controlling the motion of said propelling means, a motor for driving said fly wheel, a rubber roller by which motion is transmitted from the motor to the fly wheel normally disconnected from both the fly wheel andmotor.

4. In a recording or reproducing mechanism, means for propelling a record medium in the form of a film. a fly wheel ior controlling the motion of said propelling means, a motor for driving said fly wheel, a circuit for said motor.

a connection from said motor to said fly wheel normally disconnected from both the fly wheel and motor, and means for closing the motor cirv cuit and subsequently rendering said connections effective. j i

5. In a. recording or reproducing mechanism, means for propelling a record medium in the form of .a film, a high speed fly wheel, a motor for rotating said fly wheel, a low speed fly wheel for transmitting power from said motor to said high speed fly wheel, connections between said motor and low speed fly wheel and between said 7. In a recording or reproducing mechanism,

means for propelling a record medium in the form of a film, a high speed fly wheel, a motor for rotating said fly wheel, a low speed fly wheel for transmitting power from said motor to said high speed fly wheeL'connections between said motor I and low speed fly wheel and between said low speed fly wheel and said high speed fly wheel.

said connections being normally inefl'ective, and

means for'energizing said motor and rendering said connections effective.

8. In a recording or reproducing mechanism, means for propelling a'recorclmedium in the form of a fllm, a high speed fly wheel, a motor for rotating said fly wheel, a low speed fly wheel,

for transmitting power from said motor to said high speedfly wheel, connections between said motor and low speed flywheeland between said low speed fly wheel and said high speed flywheel, said connections being normally ineffective,

means for, energizing said motor and rendering said connections effective, and means forrenderingsaid connections ineffective on deenergizing said motor. g 9. In a recording orreproducing' mechanism, means for propelling a record medium in the 'form of a film, a. shaft for said propelling means,

a fly wheel secured to said shaft, a motor for driving said fly wheel, a second fly wheel, a resilient roller for connectingsaid motor tosaid flrst fly wheel, and a resilient roller for connecting said first fly wheel to said second fly wheel, both from said first mentioned fly wheel. 1

' 10. In a recording or reproducing mechanism, means for propelling a record medium in the said resilient rollers being normally disconnected form 01' a. fllm,a metal fly wheel for controlling the motion of said propelling means, a motor for driving said fly wheel, a motor shaft, a metal pulley on said shaft, and a rubber roller for transmitting power from said motor to said fly wheel, said rubber roller normally disconnected from both the fly wheel and motor pulley.

, WILLIAM L. WOOLF. 

